FreeBSD kernel kern code
kern_lock.c
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1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2008 Attilio Rao <attilio@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice(s), this list of conditions and the following disclaimer as
12 * the first lines of this file unmodified other than the possible
13 * addition of one or more copyright notices.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice(s), this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
19 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
22 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
24 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
25 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
28 * DAMAGE.
29 */
30
31#include "opt_ddb.h"
32#include "opt_hwpmc_hooks.h"
33
34#include <sys/cdefs.h>
35__FBSDID("$FreeBSD$");
36
37#include <sys/param.h>
38#include <sys/kdb.h>
39#include <sys/ktr.h>
40#include <sys/limits.h>
41#include <sys/lock.h>
42#include <sys/lock_profile.h>
43#include <sys/lockmgr.h>
44#include <sys/lockstat.h>
45#include <sys/mutex.h>
46#include <sys/proc.h>
47#include <sys/sleepqueue.h>
48#ifdef DEBUG_LOCKS
49#include <sys/stack.h>
50#endif
51#include <sys/sysctl.h>
52#include <sys/systm.h>
53
54#include <machine/cpu.h>
55
56#ifdef DDB
57#include <ddb/ddb.h>
58#endif
59
60#ifdef HWPMC_HOOKS
61#include <sys/pmckern.h>
62PMC_SOFT_DECLARE( , , lock, failed);
63#endif
64
65/*
66 * Hack. There should be prio_t or similar so that this is not necessary.
67 */
68_Static_assert((PRILASTFLAG * 2) - 1 <= USHRT_MAX,
69 "prio flags wont fit in u_short pri in struct lock");
70
71CTASSERT(LK_UNLOCKED == (LK_UNLOCKED &
72 ~(LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS)));
73
74#define SQ_EXCLUSIVE_QUEUE 0
75#define SQ_SHARED_QUEUE 1
76
77#ifndef INVARIANTS
78#define _lockmgr_assert(lk, what, file, line)
79#endif
80
81#define TD_SLOCKS_INC(td) ((td)->td_lk_slocks++)
82#define TD_SLOCKS_DEC(td) ((td)->td_lk_slocks--)
83
84#ifndef DEBUG_LOCKS
85#define STACK_PRINT(lk)
86#define STACK_SAVE(lk)
87#define STACK_ZERO(lk)
88#else
89#define STACK_PRINT(lk) stack_print_ddb(&(lk)->lk_stack)
90#define STACK_SAVE(lk) stack_save(&(lk)->lk_stack)
91#define STACK_ZERO(lk) stack_zero(&(lk)->lk_stack)
92#endif
93
94#define LOCK_LOG2(lk, string, arg1, arg2) \
95 if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \
96 CTR2(KTR_LOCK, (string), (arg1), (arg2))
97#define LOCK_LOG3(lk, string, arg1, arg2, arg3) \
98 if (LOCK_LOG_TEST(&(lk)->lock_object, 0)) \
99 CTR3(KTR_LOCK, (string), (arg1), (arg2), (arg3))
100
101#define GIANT_DECLARE \
102 int _i = 0; \
103 WITNESS_SAVE_DECL(Giant)
104#define GIANT_RESTORE() do { \
105 if (__predict_false(_i > 0)) { \
106 while (_i--) \
107 mtx_lock(&Giant); \
108 WITNESS_RESTORE(&Giant.lock_object, Giant); \
109 } \
110} while (0)
111#define GIANT_SAVE() do { \
112 if (__predict_false(mtx_owned(&Giant))) { \
113 WITNESS_SAVE(&Giant.lock_object, Giant); \
114 while (mtx_owned(&Giant)) { \
115 _i++; \
116 mtx_unlock(&Giant); \
117 } \
118 } \
119} while (0)
120
121static bool __always_inline
122LK_CAN_SHARE(uintptr_t x, int flags, bool fp)
123{
124
125 if ((x & (LK_SHARE | LK_EXCLUSIVE_WAITERS | LK_EXCLUSIVE_SPINNERS)) ==
126 LK_SHARE)
127 return (true);
128 if (fp || (!(x & LK_SHARE)))
129 return (false);
130 if ((curthread->td_lk_slocks != 0 && !(flags & LK_NODDLKTREAT)) ||
131 (curthread->td_pflags & TDP_DEADLKTREAT))
132 return (true);
133 return (false);
134}
135
136#define LK_TRYOP(x) \
137 ((x) & LK_NOWAIT)
138
139#define LK_CAN_WITNESS(x) \
140 (((x) & LK_NOWITNESS) == 0 && !LK_TRYOP(x))
141#define LK_TRYWIT(x) \
142 (LK_TRYOP(x) ? LOP_TRYLOCK : 0)
143
144#define lockmgr_disowned(lk) \
145 (((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == LK_KERNPROC)
146
147#define lockmgr_xlocked_v(v) \
148 (((v) & ~(LK_FLAGMASK & ~LK_SHARE)) == (uintptr_t)curthread)
149
150#define lockmgr_xlocked(lk) lockmgr_xlocked_v(lockmgr_read_value(lk))
151
152static void assert_lockmgr(const struct lock_object *lock, int how);
153#ifdef DDB
154static void db_show_lockmgr(const struct lock_object *lock);
155#endif
156static void lock_lockmgr(struct lock_object *lock, uintptr_t how);
157#ifdef KDTRACE_HOOKS
158static int owner_lockmgr(const struct lock_object *lock,
159 struct thread **owner);
160#endif
161static uintptr_t unlock_lockmgr(struct lock_object *lock);
162
163struct lock_class lock_class_lockmgr = {
164 .lc_name = "lockmgr",
165 .lc_flags = LC_RECURSABLE | LC_SLEEPABLE | LC_SLEEPLOCK | LC_UPGRADABLE,
166 .lc_assert = assert_lockmgr,
167#ifdef DDB
168 .lc_ddb_show = db_show_lockmgr,
169#endif
170 .lc_lock = lock_lockmgr,
171 .lc_unlock = unlock_lockmgr,
172#ifdef KDTRACE_HOOKS
173 .lc_owner = owner_lockmgr,
174#endif
175};
176
177static __read_mostly bool lk_adaptive = true;
178static SYSCTL_NODE(_debug, OID_AUTO, lockmgr, CTLFLAG_RD, NULL, "lockmgr debugging");
179SYSCTL_BOOL(_debug_lockmgr, OID_AUTO, adaptive_spinning, CTLFLAG_RW, &lk_adaptive,
180 0, "");
181#define lockmgr_delay locks_delay
182
183struct lockmgr_wait {
184 const char *iwmesg;
185 int ipri;
186 int itimo;
187};
188
189static bool __always_inline lockmgr_slock_try(struct lock *lk, uintptr_t *xp,
190 int flags, bool fp);
191static bool __always_inline lockmgr_sunlock_try(struct lock *lk, uintptr_t *xp);
192
193static void
194lockmgr_exit(u_int flags, struct lock_object *ilk, int wakeup_swapper)
195{
196 struct lock_class *class;
197
198 if (flags & LK_INTERLOCK) {
199 class = LOCK_CLASS(ilk);
200 class->lc_unlock(ilk);
201 }
202
203 if (__predict_false(wakeup_swapper))
204 kick_proc0();
205}
206
207static void
208lockmgr_note_shared_acquire(struct lock *lk, int contested,
209 uint64_t waittime, const char *file, int line, int flags)
210{
211
212 LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(lockmgr__acquire, lk, contested,
213 waittime, file, line, LOCKSTAT_READER);
214 LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, file, line);
215 WITNESS_LOCK(&lk->lock_object, LK_TRYWIT(flags), file, line);
216 TD_LOCKS_INC(curthread);
217 TD_SLOCKS_INC(curthread);
218 STACK_SAVE(lk);
219}
220
221static void
222lockmgr_note_shared_release(struct lock *lk, const char *file, int line)
223{
224
225 WITNESS_UNLOCK(&lk->lock_object, 0, file, line);
226 LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, file, line);
227 TD_LOCKS_DEC(curthread);
228 TD_SLOCKS_DEC(curthread);
229}
230
231static void
232lockmgr_note_exclusive_acquire(struct lock *lk, int contested,
233 uint64_t waittime, const char *file, int line, int flags)
234{
235
236 LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(lockmgr__acquire, lk, contested,
237 waittime, file, line, LOCKSTAT_WRITER);
238 LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0, lk->lk_recurse, file, line);
239 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE | LK_TRYWIT(flags), file,
240 line);
241 TD_LOCKS_INC(curthread);
242 STACK_SAVE(lk);
243}
244
245static void
246lockmgr_note_exclusive_release(struct lock *lk, const char *file, int line)
247{
248
249 if (LK_HOLDER(lockmgr_read_value(lk)) != LK_KERNPROC) {
250 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line);
251 TD_LOCKS_DEC(curthread);
252 }
253 LOCK_LOG_LOCK("XUNLOCK", &lk->lock_object, 0, lk->lk_recurse, file,
254 line);
255}
256
257static __inline struct thread *
258lockmgr_xholder(const struct lock *lk)
259{
260 uintptr_t x;
261
262 x = lockmgr_read_value(lk);
263 return ((x & LK_SHARE) ? NULL : (struct thread *)LK_HOLDER(x));
264}
265
266/*
267 * It assumes sleepq_lock held and returns with this one unheld.
268 * It also assumes the generic interlock is sane and previously checked.
269 * If LK_INTERLOCK is specified the interlock is not reacquired after the
270 * sleep.
271 */
272static __inline int
273sleeplk(struct lock *lk, u_int flags, struct lock_object *ilk,
274 const char *wmesg, int pri, int timo, int queue)
275{
276 GIANT_DECLARE;
277 struct lock_class *class;
278 int catch, error;
279
280 class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL;
281 catch = pri & PCATCH;
282 pri &= PRIMASK;
283 error = 0;
284
285 LOCK_LOG3(lk, "%s: %p blocking on the %s sleepqueue", __func__, lk,
286 (queue == SQ_EXCLUSIVE_QUEUE) ? "exclusive" : "shared");
287
288 if (flags & LK_INTERLOCK)
289 class->lc_unlock(ilk);
290 if (queue == SQ_EXCLUSIVE_QUEUE && (flags & LK_SLEEPFAIL) != 0) {
291 if (lk->lk_exslpfail < USHRT_MAX)
292 lk->lk_exslpfail++;
293 }
294 GIANT_SAVE();
295 sleepq_add(&lk->lock_object, NULL, wmesg, SLEEPQ_LK | (catch ?
296 SLEEPQ_INTERRUPTIBLE : 0), queue);
297 if ((flags & LK_TIMELOCK) && timo)
298 sleepq_set_timeout(&lk->lock_object, timo);
299
300 /*
301 * Decisional switch for real sleeping.
302 */
303 if ((flags & LK_TIMELOCK) && timo && catch)
304 error = sleepq_timedwait_sig(&lk->lock_object, pri);
305 else if ((flags & LK_TIMELOCK) && timo)
306 error = sleepq_timedwait(&lk->lock_object, pri);
307 else if (catch)
308 error = sleepq_wait_sig(&lk->lock_object, pri);
309 else
310 sleepq_wait(&lk->lock_object, pri);
311 GIANT_RESTORE();
312 if ((flags & LK_SLEEPFAIL) && error == 0)
313 error = ENOLCK;
314
315 return (error);
316}
317
318static __inline int
319wakeupshlk(struct lock *lk, const char *file, int line)
320{
321 uintptr_t v, x, orig_x;
322 u_int realexslp;
323 int queue, wakeup_swapper;
324
325 wakeup_swapper = 0;
326 for (;;) {
327 x = lockmgr_read_value(lk);
328 if (lockmgr_sunlock_try(lk, &x))
329 break;
330
331 /*
332 * We should have a sharer with waiters, so enter the hard
333 * path in order to handle wakeups correctly.
334 */
335 sleepq_lock(&lk->lock_object);
336 orig_x = lockmgr_read_value(lk);
337retry_sleepq:
338 x = orig_x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
339 v = LK_UNLOCKED;
340
341 /*
342 * If the lock has exclusive waiters, give them preference in
343 * order to avoid deadlock with shared runners up.
344 * If interruptible sleeps left the exclusive queue empty
345 * avoid a starvation for the threads sleeping on the shared
346 * queue by giving them precedence and cleaning up the
347 * exclusive waiters bit anyway.
348 * Please note that lk_exslpfail count may be lying about
349 * the real number of waiters with the LK_SLEEPFAIL flag on
350 * because they may be used in conjunction with interruptible
351 * sleeps so lk_exslpfail might be considered an 'upper limit'
352 * bound, including the edge cases.
353 */
354 realexslp = sleepq_sleepcnt(&lk->lock_object,
355 SQ_EXCLUSIVE_QUEUE);
356 if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) {
357 if (lk->lk_exslpfail != USHRT_MAX && lk->lk_exslpfail < realexslp) {
358 lk->lk_exslpfail = 0;
359 queue = SQ_EXCLUSIVE_QUEUE;
360 v |= (x & LK_SHARED_WAITERS);
361 } else {
362 lk->lk_exslpfail = 0;
363 LOCK_LOG2(lk,
364 "%s: %p has only LK_SLEEPFAIL sleepers",
365 __func__, lk);
366 LOCK_LOG2(lk,
367 "%s: %p waking up threads on the exclusive queue",
368 __func__, lk);
369 wakeup_swapper =
370 sleepq_broadcast(&lk->lock_object,
371 SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE);
372 queue = SQ_SHARED_QUEUE;
373 }
374 } else {
375 /*
376 * Exclusive waiters sleeping with LK_SLEEPFAIL on
377 * and using interruptible sleeps/timeout may have
378 * left spourious lk_exslpfail counts on, so clean
379 * it up anyway.
380 */
381 lk->lk_exslpfail = 0;
382 queue = SQ_SHARED_QUEUE;
383 }
384
385 if (lockmgr_sunlock_try(lk, &orig_x)) {
386 sleepq_release(&lk->lock_object);
387 break;
388 }
389
390 x |= LK_SHARERS_LOCK(1);
391 if (!atomic_fcmpset_rel_ptr(&lk->lk_lock, &x, v)) {
392 orig_x = x;
393 goto retry_sleepq;
394 }
395 LOCK_LOG3(lk, "%s: %p waking up threads on the %s queue",
396 __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" :
397 "exclusive");
398 wakeup_swapper |= sleepq_broadcast(&lk->lock_object, SLEEPQ_LK,
399 0, queue);
400 sleepq_release(&lk->lock_object);
401 break;
402 }
403
404 LOCKSTAT_PROFILE_RELEASE_RWLOCK(lockmgr__release, lk, LOCKSTAT_READER);
405 return (wakeup_swapper);
406}
407
408static void
409assert_lockmgr(const struct lock_object *lock, int what)
410{
411
412 panic("lockmgr locks do not support assertions");
413}
414
415static void
416lock_lockmgr(struct lock_object *lock, uintptr_t how)
417{
418
419 panic("lockmgr locks do not support sleep interlocking");
420}
421
422static uintptr_t
423unlock_lockmgr(struct lock_object *lock)
424{
425
426 panic("lockmgr locks do not support sleep interlocking");
427}
428
429#ifdef KDTRACE_HOOKS
430static int
431owner_lockmgr(const struct lock_object *lock, struct thread **owner)
432{
433
434 panic("lockmgr locks do not support owner inquiring");
435}
436#endif
437
438void
439lockinit(struct lock *lk, int pri, const char *wmesg, int timo, int flags)
440{
441 int iflags;
442
443 MPASS((flags & ~LK_INIT_MASK) == 0);
444 ASSERT_ATOMIC_LOAD_PTR(lk->lk_lock,
445 ("%s: lockmgr not aligned for %s: %p", __func__, wmesg,
446 &lk->lk_lock));
447
448 iflags = LO_SLEEPABLE | LO_UPGRADABLE;
449 if (flags & LK_CANRECURSE)
450 iflags |= LO_RECURSABLE;
451 if ((flags & LK_NODUP) == 0)
452 iflags |= LO_DUPOK;
453 if (flags & LK_NOPROFILE)
454 iflags |= LO_NOPROFILE;
455 if ((flags & LK_NOWITNESS) == 0)
456 iflags |= LO_WITNESS;
457 if (flags & LK_QUIET)
458 iflags |= LO_QUIET;
459 if (flags & LK_IS_VNODE)
460 iflags |= LO_IS_VNODE;
461 if (flags & LK_NEW)
462 iflags |= LO_NEW;
463 iflags |= flags & LK_NOSHARE;
464
465 lock_init(&lk->lock_object, &lock_class_lockmgr, wmesg, NULL, iflags);
466 lk->lk_lock = LK_UNLOCKED;
467 lk->lk_recurse = 0;
468 lk->lk_exslpfail = 0;
469 lk->lk_timo = timo;
470 lk->lk_pri = pri;
471 STACK_ZERO(lk);
472}
473
474/*
475 * XXX: Gross hacks to manipulate external lock flags after
476 * initialization. Used for certain vnode and buf locks.
477 */
478void
479lockallowshare(struct lock *lk)
480{
481
482 lockmgr_assert(lk, KA_XLOCKED);
483 lk->lock_object.lo_flags &= ~LK_NOSHARE;
484}
485
486void
487lockdisableshare(struct lock *lk)
488{
489
490 lockmgr_assert(lk, KA_XLOCKED);
491 lk->lock_object.lo_flags |= LK_NOSHARE;
492}
493
494void
495lockallowrecurse(struct lock *lk)
496{
497
498 lockmgr_assert(lk, KA_XLOCKED);
499 lk->lock_object.lo_flags |= LO_RECURSABLE;
500}
501
502void
503lockdisablerecurse(struct lock *lk)
504{
505
506 lockmgr_assert(lk, KA_XLOCKED);
507 lk->lock_object.lo_flags &= ~LO_RECURSABLE;
508}
509
510void
511lockdestroy(struct lock *lk)
512{
513
514 KASSERT(lk->lk_lock == LK_UNLOCKED, ("lockmgr still held"));
515 KASSERT(lk->lk_recurse == 0, ("lockmgr still recursed"));
516 KASSERT(lk->lk_exslpfail == 0, ("lockmgr still exclusive waiters"));
517 lock_destroy(&lk->lock_object);
518}
519
520static bool __always_inline
521lockmgr_slock_try(struct lock *lk, uintptr_t *xp, int flags, bool fp)
522{
523
524 /*
525 * If no other thread has an exclusive lock, or
526 * no exclusive waiter is present, bump the count of
527 * sharers. Since we have to preserve the state of
528 * waiters, if we fail to acquire the shared lock
529 * loop back and retry.
530 */
531 while (LK_CAN_SHARE(*xp, flags, fp)) {
532 if (atomic_fcmpset_acq_ptr(&lk->lk_lock, xp,
533 *xp + LK_ONE_SHARER)) {
534 return (true);
535 }
536 }
537 return (false);
538}
539
540static bool __always_inline
541lockmgr_sunlock_try(struct lock *lk, uintptr_t *xp)
542{
543
544 for (;;) {
545 if (LK_SHARERS(*xp) > 1 || !(*xp & LK_ALL_WAITERS)) {
546 if (atomic_fcmpset_rel_ptr(&lk->lk_lock, xp,
547 *xp - LK_ONE_SHARER))
548 return (true);
549 continue;
550 }
551 break;
552 }
553 return (false);
554}
555
556static bool
557lockmgr_slock_adaptive(struct lock_delay_arg *lda, struct lock *lk, uintptr_t *xp,
558 int flags)
559{
560 struct thread *owner;
561 uintptr_t x;
562
563 x = *xp;
564 MPASS(x != LK_UNLOCKED);
565 owner = (struct thread *)LK_HOLDER(x);
566 for (;;) {
567 MPASS(owner != curthread);
568 if (owner == (struct thread *)LK_KERNPROC)
569 return (false);
570 if ((x & LK_SHARE) && LK_SHARERS(x) > 0)
571 return (false);
572 if (owner == NULL)
573 return (false);
574 if (!TD_IS_RUNNING(owner))
575 return (false);
576 if ((x & LK_ALL_WAITERS) != 0)
577 return (false);
578 lock_delay(lda);
579 x = lockmgr_read_value(lk);
580 if (LK_CAN_SHARE(x, flags, false)) {
581 *xp = x;
582 return (true);
583 }
584 owner = (struct thread *)LK_HOLDER(x);
585 }
586}
587
588static __noinline int
589lockmgr_slock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
590 const char *file, int line, struct lockmgr_wait *lwa)
591{
592 uintptr_t tid, x;
593 int error = 0;
594 const char *iwmesg;
595 int ipri, itimo;
596
597#ifdef KDTRACE_HOOKS
598 uint64_t sleep_time = 0;
599#endif
600#ifdef LOCK_PROFILING
601 uint64_t waittime = 0;
602 int contested = 0;
603#endif
604 struct lock_delay_arg lda;
605
606 if (KERNEL_PANICKED())
607 goto out;
608
609 tid = (uintptr_t)curthread;
610
611 if (LK_CAN_WITNESS(flags))
612 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER,
613 file, line, flags & LK_INTERLOCK ? ilk : NULL);
614 x = lockmgr_read_value(lk);
615 lock_delay_arg_init(&lda, &lockmgr_delay);
616 if (!lk_adaptive)
617 flags &= ~LK_ADAPTIVE;
618 /*
619 * The lock may already be locked exclusive by curthread,
620 * avoid deadlock.
621 */
622 if (LK_HOLDER(x) == tid) {
623 LOCK_LOG2(lk,
624 "%s: %p already held in exclusive mode",
625 __func__, lk);
626 error = EDEADLK;
627 goto out;
628 }
629
630 for (;;) {
631 if (lockmgr_slock_try(lk, &x, flags, false))
632 break;
633
634 lock_profile_obtain_lock_failed(&lk->lock_object, false,
635 &contested, &waittime);
636
637 if ((flags & (LK_ADAPTIVE | LK_INTERLOCK)) == LK_ADAPTIVE) {
638 if (lockmgr_slock_adaptive(&lda, lk, &x, flags))
639 continue;
640 }
641
642#ifdef HWPMC_HOOKS
643 PMC_SOFT_CALL( , , lock, failed);
644#endif
645
646 /*
647 * If the lock is expected to not sleep just give up
648 * and return.
649 */
650 if (LK_TRYOP(flags)) {
651 LOCK_LOG2(lk, "%s: %p fails the try operation",
652 __func__, lk);
653 error = EBUSY;
654 break;
655 }
656
657 /*
658 * Acquire the sleepqueue chain lock because we
659 * probabilly will need to manipulate waiters flags.
660 */
661 sleepq_lock(&lk->lock_object);
662 x = lockmgr_read_value(lk);
663retry_sleepq:
664
665 /*
666 * if the lock can be acquired in shared mode, try
667 * again.
668 */
669 if (LK_CAN_SHARE(x, flags, false)) {
670 sleepq_release(&lk->lock_object);
671 continue;
672 }
673
674 /*
675 * Try to set the LK_SHARED_WAITERS flag. If we fail,
676 * loop back and retry.
677 */
678 if ((x & LK_SHARED_WAITERS) == 0) {
679 if (!atomic_fcmpset_acq_ptr(&lk->lk_lock, &x,
680 x | LK_SHARED_WAITERS)) {
681 goto retry_sleepq;
682 }
683 LOCK_LOG2(lk, "%s: %p set shared waiters flag",
684 __func__, lk);
685 }
686
687 if (lwa == NULL) {
688 iwmesg = lk->lock_object.lo_name;
689 ipri = lk->lk_pri;
690 itimo = lk->lk_timo;
691 } else {
692 iwmesg = lwa->iwmesg;
693 ipri = lwa->ipri;
694 itimo = lwa->itimo;
695 }
696
697 /*
698 * As far as we have been unable to acquire the
699 * shared lock and the shared waiters flag is set,
700 * we will sleep.
701 */
702#ifdef KDTRACE_HOOKS
703 sleep_time -= lockstat_nsecs(&lk->lock_object);
704#endif
705 error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
706 SQ_SHARED_QUEUE);
707#ifdef KDTRACE_HOOKS
708 sleep_time += lockstat_nsecs(&lk->lock_object);
709#endif
710 flags &= ~LK_INTERLOCK;
711 if (error) {
712 LOCK_LOG3(lk,
713 "%s: interrupted sleep for %p with %d",
714 __func__, lk, error);
715 break;
716 }
717 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
718 __func__, lk);
719 x = lockmgr_read_value(lk);
720 }
721 if (error == 0) {
722#ifdef KDTRACE_HOOKS
723 if (sleep_time != 0)
724 LOCKSTAT_RECORD4(lockmgr__block, lk, sleep_time,
725 LOCKSTAT_READER, (x & LK_SHARE) == 0,
726 (x & LK_SHARE) == 0 ? 0 : LK_SHARERS(x));
727#endif
728#ifdef LOCK_PROFILING
729 lockmgr_note_shared_acquire(lk, contested, waittime,
730 file, line, flags);
731#else
732 lockmgr_note_shared_acquire(lk, 0, 0, file, line,
733 flags);
734#endif
735 }
736
737out:
738 lockmgr_exit(flags, ilk, 0);
739 return (error);
740}
741
742static bool
743lockmgr_xlock_adaptive(struct lock_delay_arg *lda, struct lock *lk, uintptr_t *xp)
744{
745 struct thread *owner;
746 uintptr_t x;
747
748 x = *xp;
749 MPASS(x != LK_UNLOCKED);
750 owner = (struct thread *)LK_HOLDER(x);
751 for (;;) {
752 MPASS(owner != curthread);
753 if (owner == NULL)
754 return (false);
755 if ((x & LK_SHARE) && LK_SHARERS(x) > 0)
756 return (false);
757 if (owner == (struct thread *)LK_KERNPROC)
758 return (false);
759 if (!TD_IS_RUNNING(owner))
760 return (false);
761 if ((x & LK_ALL_WAITERS) != 0)
762 return (false);
763 lock_delay(lda);
764 x = lockmgr_read_value(lk);
765 if (x == LK_UNLOCKED) {
766 *xp = x;
767 return (true);
768 }
769 owner = (struct thread *)LK_HOLDER(x);
770 }
771}
772
773static __noinline int
774lockmgr_xlock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
775 const char *file, int line, struct lockmgr_wait *lwa)
776{
777 struct lock_class *class;
778 uintptr_t tid, x, v;
779 int error = 0;
780 const char *iwmesg;
781 int ipri, itimo;
782
783#ifdef KDTRACE_HOOKS
784 uint64_t sleep_time = 0;
785#endif
786#ifdef LOCK_PROFILING
787 uint64_t waittime = 0;
788 int contested = 0;
789#endif
790 struct lock_delay_arg lda;
791
792 if (KERNEL_PANICKED())
793 goto out;
794
795 tid = (uintptr_t)curthread;
796
797 if (LK_CAN_WITNESS(flags))
798 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
799 LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ?
800 ilk : NULL);
801
802 /*
803 * If curthread already holds the lock and this one is
804 * allowed to recurse, simply recurse on it.
805 */
806 if (lockmgr_xlocked(lk)) {
807 if ((flags & LK_CANRECURSE) == 0 &&
808 (lk->lock_object.lo_flags & LO_RECURSABLE) == 0) {
809 /*
810 * If the lock is expected to not panic just
811 * give up and return.
812 */
813 if (LK_TRYOP(flags)) {
814 LOCK_LOG2(lk,
815 "%s: %p fails the try operation",
816 __func__, lk);
817 error = EBUSY;
818 goto out;
819 }
820 if (flags & LK_INTERLOCK) {
821 class = LOCK_CLASS(ilk);
822 class->lc_unlock(ilk);
823 }
824 STACK_PRINT(lk);
825 panic("%s: recursing on non recursive lockmgr %p "
826 "@ %s:%d\n", __func__, lk, file, line);
827 }
828 atomic_set_ptr(&lk->lk_lock, LK_WRITER_RECURSED);
829 lk->lk_recurse++;
830 LOCK_LOG2(lk, "%s: %p recursing", __func__, lk);
831 LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0,
832 lk->lk_recurse, file, line);
833 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
834 LK_TRYWIT(flags), file, line);
835 TD_LOCKS_INC(curthread);
836 goto out;
837 }
838
839 x = LK_UNLOCKED;
840 lock_delay_arg_init(&lda, &lockmgr_delay);
841 if (!lk_adaptive)
842 flags &= ~LK_ADAPTIVE;
843 for (;;) {
844 if (x == LK_UNLOCKED) {
845 if (atomic_fcmpset_acq_ptr(&lk->lk_lock, &x, tid))
846 break;
847 continue;
848 }
849
850 lock_profile_obtain_lock_failed(&lk->lock_object, false,
851 &contested, &waittime);
852
853 if ((flags & (LK_ADAPTIVE | LK_INTERLOCK)) == LK_ADAPTIVE) {
854 if (lockmgr_xlock_adaptive(&lda, lk, &x))
855 continue;
856 }
857#ifdef HWPMC_HOOKS
858 PMC_SOFT_CALL( , , lock, failed);
859#endif
860
861 /*
862 * If the lock is expected to not sleep just give up
863 * and return.
864 */
865 if (LK_TRYOP(flags)) {
866 LOCK_LOG2(lk, "%s: %p fails the try operation",
867 __func__, lk);
868 error = EBUSY;
869 break;
870 }
871
872 /*
873 * Acquire the sleepqueue chain lock because we
874 * probabilly will need to manipulate waiters flags.
875 */
876 sleepq_lock(&lk->lock_object);
877 x = lockmgr_read_value(lk);
878retry_sleepq:
879
880 /*
881 * if the lock has been released while we spun on
882 * the sleepqueue chain lock just try again.
883 */
884 if (x == LK_UNLOCKED) {
885 sleepq_release(&lk->lock_object);
886 continue;
887 }
888
889 /*
890 * The lock can be in the state where there is a
891 * pending queue of waiters, but still no owner.
892 * This happens when the lock is contested and an
893 * owner is going to claim the lock.
894 * If curthread is the one successfully acquiring it
895 * claim lock ownership and return, preserving waiters
896 * flags.
897 */
898 v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
899 if ((x & ~v) == LK_UNLOCKED) {
900 v &= ~LK_EXCLUSIVE_SPINNERS;
901 if (atomic_fcmpset_acq_ptr(&lk->lk_lock, &x,
902 tid | v)) {
903 sleepq_release(&lk->lock_object);
904 LOCK_LOG2(lk,
905 "%s: %p claimed by a new writer",
906 __func__, lk);
907 break;
908 }
909 goto retry_sleepq;
910 }
911
912 /*
913 * Try to set the LK_EXCLUSIVE_WAITERS flag. If we
914 * fail, loop back and retry.
915 */
916 if ((x & LK_EXCLUSIVE_WAITERS) == 0) {
917 if (!atomic_fcmpset_ptr(&lk->lk_lock, &x,
918 x | LK_EXCLUSIVE_WAITERS)) {
919 goto retry_sleepq;
920 }
921 LOCK_LOG2(lk, "%s: %p set excl waiters flag",
922 __func__, lk);
923 }
924
925 if (lwa == NULL) {
926 iwmesg = lk->lock_object.lo_name;
927 ipri = lk->lk_pri;
928 itimo = lk->lk_timo;
929 } else {
930 iwmesg = lwa->iwmesg;
931 ipri = lwa->ipri;
932 itimo = lwa->itimo;
933 }
934
935 /*
936 * As far as we have been unable to acquire the
937 * exclusive lock and the exclusive waiters flag
938 * is set, we will sleep.
939 */
940#ifdef KDTRACE_HOOKS
941 sleep_time -= lockstat_nsecs(&lk->lock_object);
942#endif
943 error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
944 SQ_EXCLUSIVE_QUEUE);
945#ifdef KDTRACE_HOOKS
946 sleep_time += lockstat_nsecs(&lk->lock_object);
947#endif
948 flags &= ~LK_INTERLOCK;
949 if (error) {
950 LOCK_LOG3(lk,
951 "%s: interrupted sleep for %p with %d",
952 __func__, lk, error);
953 break;
954 }
955 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
956 __func__, lk);
957 x = lockmgr_read_value(lk);
958 }
959 if (error == 0) {
960#ifdef KDTRACE_HOOKS
961 if (sleep_time != 0)
962 LOCKSTAT_RECORD4(lockmgr__block, lk, sleep_time,
963 LOCKSTAT_WRITER, (x & LK_SHARE) == 0,
964 (x & LK_SHARE) == 0 ? 0 : LK_SHARERS(x));
965#endif
966#ifdef LOCK_PROFILING
967 lockmgr_note_exclusive_acquire(lk, contested, waittime,
968 file, line, flags);
969#else
970 lockmgr_note_exclusive_acquire(lk, 0, 0, file, line,
971 flags);
972#endif
973 }
974
975out:
976 lockmgr_exit(flags, ilk, 0);
977 return (error);
978}
979
980static __noinline int
981lockmgr_upgrade(struct lock *lk, u_int flags, struct lock_object *ilk,
982 const char *file, int line, struct lockmgr_wait *lwa)
983{
984 uintptr_t tid, v, setv;
985 int error = 0;
986 int op;
987
988 if (KERNEL_PANICKED())
989 goto out;
990
991 tid = (uintptr_t)curthread;
992
993 _lockmgr_assert(lk, KA_SLOCKED, file, line);
994
995 op = flags & LK_TYPE_MASK;
996 v = lockmgr_read_value(lk);
997 for (;;) {
998 if (LK_SHARERS(v) > 1) {
999 if (op == LK_TRYUPGRADE) {
1000 LOCK_LOG2(lk, "%s: %p failed the nowait upgrade",
1001 __func__, lk);
1002 error = EBUSY;
1003 goto out;
1004 }
1005 if (atomic_fcmpset_rel_ptr(&lk->lk_lock, &v,
1006 v - LK_ONE_SHARER)) {
1007 lockmgr_note_shared_release(lk, file, line);
1008 goto out_xlock;
1009 }
1010 continue;
1011 }
1012 MPASS((v & ~LK_ALL_WAITERS) == LK_SHARERS_LOCK(1));
1013
1014 setv = tid;
1015 setv |= (v & LK_ALL_WAITERS);
1016
1017 /*
1018 * Try to switch from one shared lock to an exclusive one.
1019 * We need to preserve waiters flags during the operation.
1020 */
1021 if (atomic_fcmpset_ptr(&lk->lk_lock, &v, setv)) {
1022 LOCK_LOG_LOCK("XUPGRADE", &lk->lock_object, 0, 0, file,
1023 line);
1024 WITNESS_UPGRADE(&lk->lock_object, LOP_EXCLUSIVE |
1025 LK_TRYWIT(flags), file, line);
1026 LOCKSTAT_RECORD0(lockmgr__upgrade, lk);
1027 TD_SLOCKS_DEC(curthread);
1028 goto out;
1029 }
1030 }
1031
1032out_xlock:
1033 error = lockmgr_xlock_hard(lk, flags, ilk, file, line, lwa);
1034 flags &= ~LK_INTERLOCK;
1035out:
1036 lockmgr_exit(flags, ilk, 0);
1037 return (error);
1038}
1039
1040int
1041lockmgr_lock_flags(struct lock *lk, u_int flags, struct lock_object *ilk,
1042 const char *file, int line)
1043{
1044 struct lock_class *class;
1045 uintptr_t x, tid;
1046 u_int op;
1047 bool locked;
1048
1049 if (KERNEL_PANICKED())
1050 return (0);
1051
1052 op = flags & LK_TYPE_MASK;
1053 locked = false;
1054 switch (op) {
1055 case LK_SHARED:
1056 if (LK_CAN_WITNESS(flags))
1057 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER,
1058 file, line, flags & LK_INTERLOCK ? ilk : NULL);
1059 if (__predict_false(lk->lock_object.lo_flags & LK_NOSHARE))
1060 break;
1061 x = lockmgr_read_value(lk);
1062 if (lockmgr_slock_try(lk, &x, flags, true)) {
1063 lockmgr_note_shared_acquire(lk, 0, 0,
1064 file, line, flags);
1065 locked = true;
1066 } else {
1067 return (lockmgr_slock_hard(lk, flags, ilk, file, line,
1068 NULL));
1069 }
1070 break;
1071 case LK_EXCLUSIVE:
1072 if (LK_CAN_WITNESS(flags))
1073 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
1074 LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ?
1075 ilk : NULL);
1076 tid = (uintptr_t)curthread;
1077 if (lockmgr_read_value(lk) == LK_UNLOCKED &&
1078 atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) {
1079 lockmgr_note_exclusive_acquire(lk, 0, 0, file, line,
1080 flags);
1081 locked = true;
1082 } else {
1083 return (lockmgr_xlock_hard(lk, flags, ilk, file, line,
1084 NULL));
1085 }
1086 break;
1087 case LK_UPGRADE:
1088 case LK_TRYUPGRADE:
1089 return (lockmgr_upgrade(lk, flags, ilk, file, line, NULL));
1090 default:
1091 break;
1092 }
1093 if (__predict_true(locked)) {
1094 if (__predict_false(flags & LK_INTERLOCK)) {
1095 class = LOCK_CLASS(ilk);
1096 class->lc_unlock(ilk);
1097 }
1098 return (0);
1099 } else {
1100 return (__lockmgr_args(lk, flags, ilk, LK_WMESG_DEFAULT,
1101 LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, file, line));
1102 }
1103}
1104
1105static __noinline int
1106lockmgr_sunlock_hard(struct lock *lk, uintptr_t x, u_int flags, struct lock_object *ilk,
1107 const char *file, int line)
1108
1109{
1110 int wakeup_swapper = 0;
1111
1112 if (KERNEL_PANICKED())
1113 goto out;
1114
1115 wakeup_swapper = wakeupshlk(lk, file, line);
1116
1117out:
1118 lockmgr_exit(flags, ilk, wakeup_swapper);
1119 return (0);
1120}
1121
1122static __noinline int
1123lockmgr_xunlock_hard(struct lock *lk, uintptr_t x, u_int flags, struct lock_object *ilk,
1124 const char *file, int line)
1125{
1126 uintptr_t tid, v;
1127 int wakeup_swapper = 0;
1128 u_int realexslp;
1129 int queue;
1130
1131 if (KERNEL_PANICKED())
1132 goto out;
1133
1134 tid = (uintptr_t)curthread;
1135
1136 /*
1137 * As first option, treact the lock as if it has not
1138 * any waiter.
1139 * Fix-up the tid var if the lock has been disowned.
1140 */
1141 if (LK_HOLDER(x) == LK_KERNPROC)
1142 tid = LK_KERNPROC;
1143
1144 /*
1145 * The lock is held in exclusive mode.
1146 * If the lock is recursed also, then unrecurse it.
1147 */
1148 if (lockmgr_recursed_v(x)) {
1149 LOCK_LOG2(lk, "%s: %p unrecursing", __func__, lk);
1150 lk->lk_recurse--;
1151 if (lk->lk_recurse == 0)
1152 atomic_clear_ptr(&lk->lk_lock, LK_WRITER_RECURSED);
1153 goto out;
1154 }
1155 if (tid != LK_KERNPROC)
1156 LOCKSTAT_PROFILE_RELEASE_RWLOCK(lockmgr__release, lk,
1157 LOCKSTAT_WRITER);
1158
1159 if (x == tid && atomic_cmpset_rel_ptr(&lk->lk_lock, tid, LK_UNLOCKED))
1160 goto out;
1161
1162 sleepq_lock(&lk->lock_object);
1163 x = lockmgr_read_value(lk);
1164 v = LK_UNLOCKED;
1165
1166 /*
1167 * If the lock has exclusive waiters, give them
1168 * preference in order to avoid deadlock with
1169 * shared runners up.
1170 * If interruptible sleeps left the exclusive queue
1171 * empty avoid a starvation for the threads sleeping
1172 * on the shared queue by giving them precedence
1173 * and cleaning up the exclusive waiters bit anyway.
1174 * Please note that lk_exslpfail count may be lying
1175 * about the real number of waiters with the
1176 * LK_SLEEPFAIL flag on because they may be used in
1177 * conjunction with interruptible sleeps so
1178 * lk_exslpfail might be considered an 'upper limit'
1179 * bound, including the edge cases.
1180 */
1181 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
1182 realexslp = sleepq_sleepcnt(&lk->lock_object, SQ_EXCLUSIVE_QUEUE);
1183 if ((x & LK_EXCLUSIVE_WAITERS) != 0 && realexslp != 0) {
1184 if (lk->lk_exslpfail != USHRT_MAX && lk->lk_exslpfail < realexslp) {
1185 lk->lk_exslpfail = 0;
1186 queue = SQ_EXCLUSIVE_QUEUE;
1187 v |= (x & LK_SHARED_WAITERS);
1188 } else {
1189 lk->lk_exslpfail = 0;
1190 LOCK_LOG2(lk,
1191 "%s: %p has only LK_SLEEPFAIL sleepers",
1192 __func__, lk);
1193 LOCK_LOG2(lk,
1194 "%s: %p waking up threads on the exclusive queue",
1195 __func__, lk);
1196 wakeup_swapper = sleepq_broadcast(&lk->lock_object,
1197 SLEEPQ_LK, 0, SQ_EXCLUSIVE_QUEUE);
1198 queue = SQ_SHARED_QUEUE;
1199 }
1200 } else {
1201 /*
1202 * Exclusive waiters sleeping with LK_SLEEPFAIL
1203 * on and using interruptible sleeps/timeout
1204 * may have left spourious lk_exslpfail counts
1205 * on, so clean it up anyway.
1206 */
1207 lk->lk_exslpfail = 0;
1208 queue = SQ_SHARED_QUEUE;
1209 }
1210
1211 LOCK_LOG3(lk, "%s: %p waking up threads on the %s queue",
1212 __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" :
1213 "exclusive");
1214 atomic_store_rel_ptr(&lk->lk_lock, v);
1215 wakeup_swapper |= sleepq_broadcast(&lk->lock_object, SLEEPQ_LK, 0, queue);
1216 sleepq_release(&lk->lock_object);
1217
1218out:
1219 lockmgr_exit(flags, ilk, wakeup_swapper);
1220 return (0);
1221}
1222
1223/*
1224 * Lightweight entry points for common operations.
1225 *
1226 * Functionality is similar to sx locks, in that none of the additional lockmgr
1227 * features are supported. To be clear, these are NOT supported:
1228 * 1. shared locking disablement
1229 * 2. returning with an error after sleep
1230 * 3. unlocking the interlock
1231 *
1232 * If in doubt, use lockmgr_lock_flags.
1233 */
1234int
1235lockmgr_slock(struct lock *lk, u_int flags, const char *file, int line)
1236{
1237 uintptr_t x;
1238
1239 MPASS((flags & LK_TYPE_MASK) == LK_SHARED);
1240 MPASS((flags & LK_INTERLOCK) == 0);
1241 MPASS((lk->lock_object.lo_flags & LK_NOSHARE) == 0);
1242
1243 if (LK_CAN_WITNESS(flags))
1244 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER,
1245 file, line, NULL);
1246 x = lockmgr_read_value(lk);
1247 if (__predict_true(lockmgr_slock_try(lk, &x, flags, true))) {
1248 lockmgr_note_shared_acquire(lk, 0, 0, file, line, flags);
1249 return (0);
1250 }
1251
1252 return (lockmgr_slock_hard(lk, flags | LK_ADAPTIVE, NULL, file, line, NULL));
1253}
1254
1255int
1256lockmgr_xlock(struct lock *lk, u_int flags, const char *file, int line)
1257{
1258 uintptr_t tid;
1259
1260 MPASS((flags & LK_TYPE_MASK) == LK_EXCLUSIVE);
1261 MPASS((flags & LK_INTERLOCK) == 0);
1262
1263 if (LK_CAN_WITNESS(flags))
1264 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
1265 LOP_EXCLUSIVE, file, line, NULL);
1266 tid = (uintptr_t)curthread;
1267 if (atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) {
1268 lockmgr_note_exclusive_acquire(lk, 0, 0, file, line,
1269 flags);
1270 return (0);
1271 }
1272
1273 return (lockmgr_xlock_hard(lk, flags | LK_ADAPTIVE, NULL, file, line, NULL));
1274}
1275
1276int
1277lockmgr_unlock(struct lock *lk)
1278{
1279 uintptr_t x, tid;
1280 const char *file;
1281 int line;
1282
1283 file = __FILE__;
1284 line = __LINE__;
1285
1286 _lockmgr_assert(lk, KA_LOCKED, file, line);
1287 x = lockmgr_read_value(lk);
1288 if (__predict_true(x & LK_SHARE) != 0) {
1289 lockmgr_note_shared_release(lk, file, line);
1290 if (lockmgr_sunlock_try(lk, &x)) {
1291 LOCKSTAT_PROFILE_RELEASE_RWLOCK(lockmgr__release, lk, LOCKSTAT_READER);
1292 } else {
1293 return (lockmgr_sunlock_hard(lk, x, LK_RELEASE, NULL, file, line));
1294 }
1295 } else {
1296 tid = (uintptr_t)curthread;
1297 lockmgr_note_exclusive_release(lk, file, line);
1298 if (x == tid && atomic_cmpset_rel_ptr(&lk->lk_lock, tid, LK_UNLOCKED)) {
1299 LOCKSTAT_PROFILE_RELEASE_RWLOCK(lockmgr__release, lk,LOCKSTAT_WRITER);
1300 } else {
1301 return (lockmgr_xunlock_hard(lk, x, LK_RELEASE, NULL, file, line));
1302 }
1303 }
1304 return (0);
1305}
1306
1307int
1308__lockmgr_args(struct lock *lk, u_int flags, struct lock_object *ilk,
1309 const char *wmesg, int pri, int timo, const char *file, int line)
1310{
1311 GIANT_DECLARE;
1312 struct lockmgr_wait lwa;
1313 struct lock_class *class;
1314 const char *iwmesg;
1315 uintptr_t tid, v, x;
1316 u_int op, realexslp;
1317 int error, ipri, itimo, queue, wakeup_swapper;
1318#ifdef LOCK_PROFILING
1319 uint64_t waittime = 0;
1320 int contested = 0;
1321#endif
1322
1323 if (KERNEL_PANICKED())
1324 return (0);
1325
1326 error = 0;
1327 tid = (uintptr_t)curthread;
1328 op = (flags & LK_TYPE_MASK);
1329 iwmesg = (wmesg == LK_WMESG_DEFAULT) ? lk->lock_object.lo_name : wmesg;
1330 ipri = (pri == LK_PRIO_DEFAULT) ? lk->lk_pri : pri;
1331 itimo = (timo == LK_TIMO_DEFAULT) ? lk->lk_timo : timo;
1332
1333 lwa.iwmesg = iwmesg;
1334 lwa.ipri = ipri;
1335 lwa.itimo = itimo;
1336
1337 MPASS((flags & ~LK_TOTAL_MASK) == 0);
1338 KASSERT((op & (op - 1)) == 0,
1339 ("%s: Invalid requested operation @ %s:%d", __func__, file, line));
1340 KASSERT((flags & (LK_NOWAIT | LK_SLEEPFAIL)) == 0 ||
1341 (op != LK_DOWNGRADE && op != LK_RELEASE),
1342 ("%s: Invalid flags in regard of the operation desired @ %s:%d",
1343 __func__, file, line));
1344 KASSERT((flags & LK_INTERLOCK) == 0 || ilk != NULL,
1345 ("%s: LK_INTERLOCK passed without valid interlock @ %s:%d",
1346 __func__, file, line));
1347 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
1348 ("%s: idle thread %p on lockmgr %s @ %s:%d", __func__, curthread,
1349 lk->lock_object.lo_name, file, line));
1350
1351 class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL;
1352
1353 if (lk->lock_object.lo_flags & LK_NOSHARE) {
1354 switch (op) {
1355 case LK_SHARED:
1356 op = LK_EXCLUSIVE;
1357 break;
1358 case LK_UPGRADE:
1359 case LK_TRYUPGRADE:
1360 case LK_DOWNGRADE:
1361 _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED,
1362 file, line);
1363 if (flags & LK_INTERLOCK)
1364 class->lc_unlock(ilk);
1365 return (0);
1366 }
1367 }
1368
1369 wakeup_swapper = 0;
1370 switch (op) {
1371 case LK_SHARED:
1372 return (lockmgr_slock_hard(lk, flags, ilk, file, line, &lwa));
1373 break;
1374 case LK_UPGRADE:
1375 case LK_TRYUPGRADE:
1376 return (lockmgr_upgrade(lk, flags, ilk, file, line, &lwa));
1377 break;
1378 case LK_EXCLUSIVE:
1379 return (lockmgr_xlock_hard(lk, flags, ilk, file, line, &lwa));
1380 break;
1381 case LK_DOWNGRADE:
1382 _lockmgr_assert(lk, KA_XLOCKED, file, line);
1383 WITNESS_DOWNGRADE(&lk->lock_object, 0, file, line);
1384
1385 /*
1386 * Panic if the lock is recursed.
1387 */
1388 if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) {
1389 if (flags & LK_INTERLOCK)
1390 class->lc_unlock(ilk);
1391 panic("%s: downgrade a recursed lockmgr %s @ %s:%d\n",
1392 __func__, iwmesg, file, line);
1393 }
1394 TD_SLOCKS_INC(curthread);
1395
1396 /*
1397 * In order to preserve waiters flags, just spin.
1398 */
1399 for (;;) {
1400 x = lockmgr_read_value(lk);
1401 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
1402 x &= LK_ALL_WAITERS;
1403 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
1404 LK_SHARERS_LOCK(1) | x))
1405 break;
1406 cpu_spinwait();
1407 }
1408 LOCK_LOG_LOCK("XDOWNGRADE", &lk->lock_object, 0, 0, file, line);
1409 LOCKSTAT_RECORD0(lockmgr__downgrade, lk);
1410 break;
1411 case LK_RELEASE:
1412 _lockmgr_assert(lk, KA_LOCKED, file, line);
1413 x = lockmgr_read_value(lk);
1414
1415 if (__predict_true(x & LK_SHARE) != 0) {
1416 lockmgr_note_shared_release(lk, file, line);
1417 return (lockmgr_sunlock_hard(lk, x, flags, ilk, file, line));
1418 } else {
1419 lockmgr_note_exclusive_release(lk, file, line);
1420 return (lockmgr_xunlock_hard(lk, x, flags, ilk, file, line));
1421 }
1422 break;
1423 case LK_DRAIN:
1424 if (LK_CAN_WITNESS(flags))
1425 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
1426 LOP_EXCLUSIVE, file, line, flags & LK_INTERLOCK ?
1427 ilk : NULL);
1428
1429 /*
1430 * Trying to drain a lock we already own will result in a
1431 * deadlock.
1432 */
1433 if (lockmgr_xlocked(lk)) {
1434 if (flags & LK_INTERLOCK)
1435 class->lc_unlock(ilk);
1436 panic("%s: draining %s with the lock held @ %s:%d\n",
1437 __func__, iwmesg, file, line);
1438 }
1439
1440 for (;;) {
1441 if (lk->lk_lock == LK_UNLOCKED &&
1442 atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid))
1443 break;
1444
1445#ifdef HWPMC_HOOKS
1446 PMC_SOFT_CALL( , , lock, failed);
1447#endif
1448 lock_profile_obtain_lock_failed(&lk->lock_object, false,
1449 &contested, &waittime);
1450
1451 /*
1452 * If the lock is expected to not sleep just give up
1453 * and return.
1454 */
1455 if (LK_TRYOP(flags)) {
1456 LOCK_LOG2(lk, "%s: %p fails the try operation",
1457 __func__, lk);
1458 error = EBUSY;
1459 break;
1460 }
1461
1462 /*
1463 * Acquire the sleepqueue chain lock because we
1464 * probabilly will need to manipulate waiters flags.
1465 */
1466 sleepq_lock(&lk->lock_object);
1467 x = lockmgr_read_value(lk);
1468
1469 /*
1470 * if the lock has been released while we spun on
1471 * the sleepqueue chain lock just try again.
1472 */
1473 if (x == LK_UNLOCKED) {
1474 sleepq_release(&lk->lock_object);
1475 continue;
1476 }
1477
1478 v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
1479 if ((x & ~v) == LK_UNLOCKED) {
1480 v = (x & ~LK_EXCLUSIVE_SPINNERS);
1481
1482 /*
1483 * If interruptible sleeps left the exclusive
1484 * queue empty avoid a starvation for the
1485 * threads sleeping on the shared queue by
1486 * giving them precedence and cleaning up the
1487 * exclusive waiters bit anyway.
1488 * Please note that lk_exslpfail count may be
1489 * lying about the real number of waiters with
1490 * the LK_SLEEPFAIL flag on because they may
1491 * be used in conjunction with interruptible
1492 * sleeps so lk_exslpfail might be considered
1493 * an 'upper limit' bound, including the edge
1494 * cases.
1495 */
1496 if (v & LK_EXCLUSIVE_WAITERS) {
1497 queue = SQ_EXCLUSIVE_QUEUE;
1498 v &= ~LK_EXCLUSIVE_WAITERS;
1499 } else {
1500 /*
1501 * Exclusive waiters sleeping with
1502 * LK_SLEEPFAIL on and using
1503 * interruptible sleeps/timeout may
1504 * have left spourious lk_exslpfail
1505 * counts on, so clean it up anyway.
1506 */
1507 MPASS(v & LK_SHARED_WAITERS);
1508 lk->lk_exslpfail = 0;
1509 queue = SQ_SHARED_QUEUE;
1510 v &= ~LK_SHARED_WAITERS;
1511 }
1512 if (queue == SQ_EXCLUSIVE_QUEUE) {
1513 realexslp =
1514 sleepq_sleepcnt(&lk->lock_object,
1515 SQ_EXCLUSIVE_QUEUE);
1516 if (lk->lk_exslpfail >= realexslp) {
1517 lk->lk_exslpfail = 0;
1518 queue = SQ_SHARED_QUEUE;
1519 v &= ~LK_SHARED_WAITERS;
1520 if (realexslp != 0) {
1521 LOCK_LOG2(lk,
1522 "%s: %p has only LK_SLEEPFAIL sleepers",
1523 __func__, lk);
1524 LOCK_LOG2(lk,
1525 "%s: %p waking up threads on the exclusive queue",
1526 __func__, lk);
1527 wakeup_swapper =
1528 sleepq_broadcast(
1529 &lk->lock_object,
1530 SLEEPQ_LK, 0,
1531 SQ_EXCLUSIVE_QUEUE);
1532 }
1533 } else
1534 lk->lk_exslpfail = 0;
1535 }
1536 if (!atomic_cmpset_ptr(&lk->lk_lock, x, v)) {
1537 sleepq_release(&lk->lock_object);
1538 continue;
1539 }
1540 LOCK_LOG3(lk,
1541 "%s: %p waking up all threads on the %s queue",
1542 __func__, lk, queue == SQ_SHARED_QUEUE ?
1543 "shared" : "exclusive");
1544 wakeup_swapper |= sleepq_broadcast(
1545 &lk->lock_object, SLEEPQ_LK, 0, queue);
1546
1547 /*
1548 * If shared waiters have been woken up we need
1549 * to wait for one of them to acquire the lock
1550 * before to set the exclusive waiters in
1551 * order to avoid a deadlock.
1552 */
1553 if (queue == SQ_SHARED_QUEUE) {
1554 for (v = lk->lk_lock;
1555 (v & LK_SHARE) && !LK_SHARERS(v);
1556 v = lk->lk_lock)
1557 cpu_spinwait();
1558 }
1559 }
1560
1561 /*
1562 * Try to set the LK_EXCLUSIVE_WAITERS flag. If we
1563 * fail, loop back and retry.
1564 */
1565 if ((x & LK_EXCLUSIVE_WAITERS) == 0) {
1566 if (!atomic_cmpset_ptr(&lk->lk_lock, x,
1567 x | LK_EXCLUSIVE_WAITERS)) {
1568 sleepq_release(&lk->lock_object);
1569 continue;
1570 }
1571 LOCK_LOG2(lk, "%s: %p set drain waiters flag",
1572 __func__, lk);
1573 }
1574
1575 /*
1576 * As far as we have been unable to acquire the
1577 * exclusive lock and the exclusive waiters flag
1578 * is set, we will sleep.
1579 */
1580 if (flags & LK_INTERLOCK) {
1581 class->lc_unlock(ilk);
1582 flags &= ~LK_INTERLOCK;
1583 }
1584 GIANT_SAVE();
1585 sleepq_add(&lk->lock_object, NULL, iwmesg, SLEEPQ_LK,
1586 SQ_EXCLUSIVE_QUEUE);
1587 sleepq_wait(&lk->lock_object, ipri & PRIMASK);
1588 GIANT_RESTORE();
1589 LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
1590 __func__, lk);
1591 }
1592
1593 if (error == 0) {
1594 lock_profile_obtain_lock_success(&lk->lock_object,
1595 false, contested, waittime, file, line);
1596 LOCK_LOG_LOCK("DRAIN", &lk->lock_object, 0,
1597 lk->lk_recurse, file, line);
1598 WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
1599 LK_TRYWIT(flags), file, line);
1600 TD_LOCKS_INC(curthread);
1601 STACK_SAVE(lk);
1602 }
1603 break;
1604 default:
1605 if (flags & LK_INTERLOCK)
1606 class->lc_unlock(ilk);
1607 panic("%s: unknown lockmgr request 0x%x\n", __func__, op);
1608 }
1609
1610 if (flags & LK_INTERLOCK)
1611 class->lc_unlock(ilk);
1612 if (wakeup_swapper)
1613 kick_proc0();
1614
1615 return (error);
1616}
1617
1618void
1619_lockmgr_disown(struct lock *lk, const char *file, int line)
1620{
1621 uintptr_t tid, x;
1622
1623 if (SCHEDULER_STOPPED())
1624 return;
1625
1626 tid = (uintptr_t)curthread;
1627 _lockmgr_assert(lk, KA_XLOCKED, file, line);
1628
1629 /*
1630 * Panic if the lock is recursed.
1631 */
1632 if (lockmgr_xlocked(lk) && lockmgr_recursed(lk))
1633 panic("%s: disown a recursed lockmgr @ %s:%d\n",
1634 __func__, file, line);
1635
1636 /*
1637 * If the owner is already LK_KERNPROC just skip the whole operation.
1638 */
1639 if (LK_HOLDER(lk->lk_lock) != tid)
1640 return;
1641 lock_profile_release_lock(&lk->lock_object, false);
1642 LOCKSTAT_RECORD1(lockmgr__disown, lk, LOCKSTAT_WRITER);
1643 LOCK_LOG_LOCK("XDISOWN", &lk->lock_object, 0, 0, file, line);
1644 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line);
1645 TD_LOCKS_DEC(curthread);
1646 STACK_SAVE(lk);
1647
1648 /*
1649 * In order to preserve waiters flags, just spin.
1650 */
1651 for (;;) {
1652 x = lockmgr_read_value(lk);
1653 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
1654 x &= LK_ALL_WAITERS;
1655 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
1656 LK_KERNPROC | x))
1657 return;
1658 cpu_spinwait();
1659 }
1660}
1661
1662void
1663lockmgr_printinfo(const struct lock *lk)
1664{
1665 struct thread *td;
1666 uintptr_t x;
1667
1668 if (lk->lk_lock == LK_UNLOCKED)
1669 printf("lock type %s: UNLOCKED\n", lk->lock_object.lo_name);
1670 else if (lk->lk_lock & LK_SHARE)
1671 printf("lock type %s: SHARED (count %ju)\n",
1672 lk->lock_object.lo_name,
1673 (uintmax_t)LK_SHARERS(lk->lk_lock));
1674 else {
1675 td = lockmgr_xholder(lk);
1676 if (td == (struct thread *)LK_KERNPROC)
1677 printf("lock type %s: EXCL by KERNPROC\n",
1678 lk->lock_object.lo_name);
1679 else
1680 printf("lock type %s: EXCL by thread %p "
1681 "(pid %d, %s, tid %d)\n", lk->lock_object.lo_name,
1682 td, td->td_proc->p_pid, td->td_proc->p_comm,
1683 td->td_tid);
1684 }
1685
1686 x = lk->lk_lock;
1687 if (x & LK_EXCLUSIVE_WAITERS)
1688 printf(" with exclusive waiters pending\n");
1689 if (x & LK_SHARED_WAITERS)
1690 printf(" with shared waiters pending\n");
1691 if (x & LK_EXCLUSIVE_SPINNERS)
1692 printf(" with exclusive spinners pending\n");
1693
1694 STACK_PRINT(lk);
1695}
1696
1697int
1698lockstatus(const struct lock *lk)
1699{
1700 uintptr_t v, x;
1701 int ret;
1702
1703 ret = LK_SHARED;
1704 x = lockmgr_read_value(lk);
1705 v = LK_HOLDER(x);
1706
1707 if ((x & LK_SHARE) == 0) {
1708 if (v == (uintptr_t)curthread || v == LK_KERNPROC)
1709 ret = LK_EXCLUSIVE;
1710 else
1711 ret = LK_EXCLOTHER;
1712 } else if (x == LK_UNLOCKED)
1713 ret = 0;
1714
1715 return (ret);
1716}
1717
1718#ifdef INVARIANT_SUPPORT
1719
1720FEATURE(invariant_support,
1721 "Support for modules compiled with INVARIANTS option");
1722
1723#ifndef INVARIANTS
1724#undef _lockmgr_assert
1725#endif
1726
1727void
1728_lockmgr_assert(const struct lock *lk, int what, const char *file, int line)
1729{
1730 int slocked = 0;
1731
1732 if (KERNEL_PANICKED())
1733 return;
1734 switch (what) {
1735 case KA_SLOCKED:
1736 case KA_SLOCKED | KA_NOTRECURSED:
1737 case KA_SLOCKED | KA_RECURSED:
1738 slocked = 1;
1739 case KA_LOCKED:
1740 case KA_LOCKED | KA_NOTRECURSED:
1741 case KA_LOCKED | KA_RECURSED:
1742#ifdef WITNESS
1743
1744 /*
1745 * We cannot trust WITNESS if the lock is held in exclusive
1746 * mode and a call to lockmgr_disown() happened.
1747 * Workaround this skipping the check if the lock is held in
1748 * exclusive mode even for the KA_LOCKED case.
1749 */
1750 if (slocked || (lk->lk_lock & LK_SHARE)) {
1751 witness_assert(&lk->lock_object, what, file, line);
1752 break;
1753 }
1754#endif
1755 if (lk->lk_lock == LK_UNLOCKED ||
1756 ((lk->lk_lock & LK_SHARE) == 0 && (slocked ||
1757 (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk)))))
1758 panic("Lock %s not %slocked @ %s:%d\n",
1759 lk->lock_object.lo_name, slocked ? "share" : "",
1760 file, line);
1761
1762 if ((lk->lk_lock & LK_SHARE) == 0) {
1763 if (lockmgr_recursed(lk)) {
1764 if (what & KA_NOTRECURSED)
1765 panic("Lock %s recursed @ %s:%d\n",
1766 lk->lock_object.lo_name, file,
1767 line);
1768 } else if (what & KA_RECURSED)
1769 panic("Lock %s not recursed @ %s:%d\n",
1770 lk->lock_object.lo_name, file, line);
1771 }
1772 break;
1773 case KA_XLOCKED:
1774 case KA_XLOCKED | KA_NOTRECURSED:
1775 case KA_XLOCKED | KA_RECURSED:
1776 if (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk))
1777 panic("Lock %s not exclusively locked @ %s:%d\n",
1778 lk->lock_object.lo_name, file, line);
1779 if (lockmgr_recursed(lk)) {
1780 if (what & KA_NOTRECURSED)
1781 panic("Lock %s recursed @ %s:%d\n",
1782 lk->lock_object.lo_name, file, line);
1783 } else if (what & KA_RECURSED)
1784 panic("Lock %s not recursed @ %s:%d\n",
1785 lk->lock_object.lo_name, file, line);
1786 break;
1787 case KA_UNLOCKED:
1788 if (lockmgr_xlocked(lk) || lockmgr_disowned(lk))
1789 panic("Lock %s exclusively locked @ %s:%d\n",
1790 lk->lock_object.lo_name, file, line);
1791 break;
1792 default:
1793 panic("Unknown lockmgr assertion: %d @ %s:%d\n", what, file,
1794 line);
1795 }
1796}
1797#endif
1798
1799#ifdef DDB
1800int
1801lockmgr_chain(struct thread *td, struct thread **ownerp)
1802{
1803 const struct lock *lk;
1804
1805 lk = td->td_wchan;
1806
1807 if (LOCK_CLASS(&lk->lock_object) != &lock_class_lockmgr)
1808 return (0);
1809 db_printf("blocked on lockmgr %s", lk->lock_object.lo_name);
1810 if (lk->lk_lock & LK_SHARE)
1811 db_printf("SHARED (count %ju)\n",
1812 (uintmax_t)LK_SHARERS(lk->lk_lock));
1813 else
1814 db_printf("EXCL\n");
1815 *ownerp = lockmgr_xholder(lk);
1816
1817 return (1);
1818}
1819
1820static void
1821db_show_lockmgr(const struct lock_object *lock)
1822{
1823 struct thread *td;
1824 const struct lock *lk;
1825
1826 lk = (const struct lock *)lock;
1827
1828 db_printf(" state: ");
1829 if (lk->lk_lock == LK_UNLOCKED)
1830 db_printf("UNLOCKED\n");
1831 else if (lk->lk_lock & LK_SHARE)
1832 db_printf("SLOCK: %ju\n", (uintmax_t)LK_SHARERS(lk->lk_lock));
1833 else {
1834 td = lockmgr_xholder(lk);
1835 if (td == (struct thread *)LK_KERNPROC)
1836 db_printf("XLOCK: LK_KERNPROC\n");
1837 else
1838 db_printf("XLOCK: %p (tid %d, pid %d, \"%s\")\n", td,
1839 td->td_tid, td->td_proc->p_pid,
1840 td->td_proc->p_comm);
1841 if (lockmgr_recursed(lk))
1842 db_printf(" recursed: %d\n", lk->lk_recurse);
1843 }
1844 db_printf(" waiters: ");
1845 switch (lk->lk_lock & LK_ALL_WAITERS) {
1846 case LK_SHARED_WAITERS:
1847 db_printf("shared\n");
1848 break;
1849 case LK_EXCLUSIVE_WAITERS:
1850 db_printf("exclusive\n");
1851 break;
1852 case LK_ALL_WAITERS:
1853 db_printf("shared and exclusive\n");
1854 break;
1855 default:
1856 db_printf("none\n");
1857 }
1858 db_printf(" spinners: ");
1859 if (lk->lk_lock & LK_EXCLUSIVE_SPINNERS)
1860 db_printf("exclusive\n");
1861 else
1862 db_printf("none\n");
1863}
1864#endif
FEATURE
FEATURE(kdtrace_hooks, "Kernel DTrace hooks which are required to load DTrace kernel modules")
GIANT_SAVE
#define GIANT_SAVE()
Definition: kern_lock.c:111
SYSCTL_BOOL
SYSCTL_BOOL(_debug_lockmgr, OID_AUTO, adaptive_spinning, CTLFLAG_RW, &lk_adaptive, 0, "")
lockdestroy
void lockdestroy(struct lock *lk)
Definition: kern_lock.c:511
lockmgr_disowned
#define lockmgr_disowned(lk)
Definition: kern_lock.c:144
lockstatus
int lockstatus(const struct lock *lk)
Definition: kern_lock.c:1698
lockmgr_delay
#define lockmgr_delay
Definition: kern_lock.c:181
lockmgr_printinfo
void lockmgr_printinfo(const struct lock *lk)
Definition: kern_lock.c:1663
lockmgr_note_shared_acquire
static void lockmgr_note_shared_acquire(struct lock *lk, int contested, uint64_t waittime, const char *file, int line, int flags)
Definition: kern_lock.c:208
SYSCTL_NODE
static SYSCTL_NODE(_debug, OID_AUTO, lockmgr, CTLFLAG_RD, NULL, "lockmgr debugging")
LK_CAN_SHARE
static bool __always_inline LK_CAN_SHARE(uintptr_t x, int flags, bool fp)
Definition: kern_lock.c:122
lockallowshare
void lockallowshare(struct lock *lk)
Definition: kern_lock.c:479
LK_TRYOP
#define LK_TRYOP(x)
Definition: kern_lock.c:136
SQ_EXCLUSIVE_QUEUE
#define SQ_EXCLUSIVE_QUEUE
Definition: kern_lock.c:74
GIANT_RESTORE
#define GIANT_RESTORE()
Definition: kern_lock.c:104
lockinit
void lockinit(struct lock *lk, int pri, const char *wmesg, int timo, int flags)
Definition: kern_lock.c:439
assert_lockmgr
static void assert_lockmgr(const struct lock_object *lock, int how)
Definition: kern_lock.c:409
STACK_PRINT
#define STACK_PRINT(lk)
Definition: kern_lock.c:85
lockallowrecurse
void lockallowrecurse(struct lock *lk)
Definition: kern_lock.c:495
__lockmgr_args
int __lockmgr_args(struct lock *lk, u_int flags, struct lock_object *ilk, const char *wmesg, int pri, int timo, const char *file, int line)
Definition: kern_lock.c:1308
wakeupshlk
static __inline int wakeupshlk(struct lock *lk, const char *file, int line)
Definition: kern_lock.c:319
LK_CAN_WITNESS
#define LK_CAN_WITNESS(x)
Definition: kern_lock.c:139
lockmgr_slock_adaptive
static bool lockmgr_slock_adaptive(struct lock_delay_arg *lda, struct lock *lk, uintptr_t *xp, int flags)
Definition: kern_lock.c:557
lockmgr_exit
static void lockmgr_exit(u_int flags, struct lock_object *ilk, int wakeup_swapper)
Definition: kern_lock.c:194
lockdisablerecurse
void lockdisablerecurse(struct lock *lk)
Definition: kern_lock.c:503
STACK_SAVE
#define STACK_SAVE(lk)
Definition: kern_lock.c:86
sleeplk
static __inline int sleeplk(struct lock *lk, u_int flags, struct lock_object *ilk, const char *wmesg, int pri, int timo, int queue)
Definition: kern_lock.c:273
lockmgr_note_shared_release
static void lockmgr_note_shared_release(struct lock *lk, const char *file, int line)
Definition: kern_lock.c:222
lockmgr_xlocked
#define lockmgr_xlocked(lk)
Definition: kern_lock.c:150
LK_TRYWIT
#define LK_TRYWIT(x)
Definition: kern_lock.c:141
lockmgr_xlock_adaptive
static bool lockmgr_xlock_adaptive(struct lock_delay_arg *lda, struct lock *lk, uintptr_t *xp)
Definition: kern_lock.c:743
SQ_SHARED_QUEUE
#define SQ_SHARED_QUEUE
Definition: kern_lock.c:75
lockmgr_slock_try
static bool __always_inline lockmgr_slock_try(struct lock *lk, uintptr_t *xp, int flags, bool fp)
Definition: kern_lock.c:521
lockmgr_upgrade
static __noinline int lockmgr_upgrade(struct lock *lk, u_int flags, struct lock_object *ilk, const char *file, int line, struct lockmgr_wait *lwa)
Definition: kern_lock.c:981
lockmgr_xlock
int lockmgr_xlock(struct lock *lk, u_int flags, const char *file, int line)
Definition: kern_lock.c:1256
STACK_ZERO
#define STACK_ZERO(lk)
Definition: kern_lock.c:87
TD_SLOCKS_DEC
#define TD_SLOCKS_DEC(td)
Definition: kern_lock.c:82
lockmgr_sunlock_hard
static __noinline int lockmgr_sunlock_hard(struct lock *lk, uintptr_t x, u_int flags, struct lock_object *ilk, const char *file, int line)
Definition: kern_lock.c:1106
lockmgr_lock_flags
int lockmgr_lock_flags(struct lock *lk, u_int flags, struct lock_object *ilk, const char *file, int line)
Definition: kern_lock.c:1041
lock_class_lockmgr
struct lock_class lock_class_lockmgr
Definition: kern_lock.c:163
__FBSDID
__FBSDID("$FreeBSD$")
_Static_assert
_Static_assert((PRILASTFLAG *2) - 1<=USHRT_MAX, "prio flags wont fit in u_short pri in struct lock")
GIANT_DECLARE
#define GIANT_DECLARE
Definition: kern_lock.c:101
lockmgr_sunlock_try
static bool __always_inline lockmgr_sunlock_try(struct lock *lk, uintptr_t *xp)
Definition: kern_lock.c:541
lockmgr_xlock_hard
static __noinline int lockmgr_xlock_hard(struct lock *lk, u_int flags, struct lock_object *ilk, const char *file, int line, struct lockmgr_wait *lwa)
Definition: kern_lock.c:774
LOCK_LOG2
#define LOCK_LOG2(lk, string, arg1, arg2)
Definition: kern_lock.c:94
lockmgr_slock
int lockmgr_slock(struct lock *lk, u_int flags, const char *file, int line)
Definition: kern_lock.c:1235
lk_adaptive
static __read_mostly bool lk_adaptive
Definition: kern_lock.c:177
lockmgr_xholder
static __inline struct thread * lockmgr_xholder(const struct lock *lk)
Definition: kern_lock.c:258
lockmgr_unlock
int lockmgr_unlock(struct lock *lk)
Definition: kern_lock.c:1277
lockmgr_slock_hard
static __noinline int lockmgr_slock_hard(struct lock *lk, u_int flags, struct lock_object *ilk, const char *file, int line, struct lockmgr_wait *lwa)
Definition: kern_lock.c:589
LOCK_LOG3
#define LOCK_LOG3(lk, string, arg1, arg2, arg3)
Definition: kern_lock.c:97
lock_lockmgr
static void lock_lockmgr(struct lock_object *lock, uintptr_t how)
Definition: kern_lock.c:416
lockmgr_note_exclusive_acquire
static void lockmgr_note_exclusive_acquire(struct lock *lk, int contested, uint64_t waittime, const char *file, int line, int flags)
Definition: kern_lock.c:232
_lockmgr_disown
void _lockmgr_disown(struct lock *lk, const char *file, int line)
Definition: kern_lock.c:1619
TD_SLOCKS_INC
#define TD_SLOCKS_INC(td)
Definition: kern_lock.c:81
_lockmgr_assert
#define _lockmgr_assert(lk, what, file, line)
Definition: kern_lock.c:78
lockmgr_xunlock_hard
static __noinline int lockmgr_xunlock_hard(struct lock *lk, uintptr_t x, u_int flags, struct lock_object *ilk, const char *file, int line)
Definition: kern_lock.c:1123
lockmgr_note_exclusive_release
static void lockmgr_note_exclusive_release(struct lock *lk, const char *file, int line)
Definition: kern_lock.c:246
lockdisableshare
void lockdisableshare(struct lock *lk)
Definition: kern_lock.c:487
CTASSERT
CTASSERT(LK_UNLOCKED==(LK_UNLOCKED &~(LK_ALL_WAITERS|LK_EXCLUSIVE_SPINNERS)))
unlock_lockmgr
static uintptr_t unlock_lockmgr(struct lock_object *lock)
Definition: kern_lock.c:423
lockstat_nsecs
uint64_t lockstat_nsecs(struct lock_object *lo)
Definition: kern_lockstat.c:78
panic
void panic(const char *fmt,...)
Definition: kern_shutdown.c:884
lockmgr_wait
Definition: kern_lock.c:183
lockmgr_wait::iwmesg
const char * iwmesg
Definition: kern_lock.c:184
lockmgr_wait::ipri
int ipri
Definition: kern_lock.c:185
lockmgr_wait::itimo
int itimo
Definition: kern_lock.c:186
__read_mostly
static bool kasan_enabled __read_mostly
Definition: subr_asan.c:95
kdb_active
u_char __read_frequently kdb_active
Definition: subr_kdb.c:56
lock_destroy
void lock_destroy(struct lock_object *lock)
Definition: subr_lock.c:108
lock_init
void lock_init(struct lock_object *lock, struct lock_class *class, const char *name, const char *type, int flags)
Definition: subr_lock.c:83
lock_delay
void lock_delay(struct lock_delay_arg *la)
Definition: subr_lock.c:132
printf
int printf(const char *fmt,...)
Definition: subr_prf.c:397
sleepq_release
void sleepq_release(const void *wchan)
Definition: subr_sleepqueue.c:294
sleepq_wait_sig
int sleepq_wait_sig(const void *wchan, int pri)
Definition: subr_sleepqueue.c:667
sleepq_broadcast
int sleepq_broadcast(const void *wchan, int flags, int pri, int queue)
Definition: subr_sleepqueue.c:992
sleepq_timedwait_sig
int sleepq_timedwait_sig(const void *wchan, int pri)
Definition: subr_sleepqueue.c:700
sleepq_timedwait
int sleepq_timedwait(const void *wchan, int pri)
Definition: subr_sleepqueue.c:682
sleepq_sleepcnt
u_int sleepq_sleepcnt(const void *wchan, int queue)
Definition: subr_sleepqueue.c:424
sleepq_add
void sleepq_add(const void *wchan, struct lock_object *lock, const char *wmesg, int flags, int queue)
Definition: subr_sleepqueue.c:309
sleepq_wait
void sleepq_wait(const void *wchan, int pri)
Definition: subr_sleepqueue.c:652
sleepq_lock
void sleepq_lock(const void *wchan)
Definition: subr_sleepqueue.c:262
flags
uint16_t flags
Definition: subr_stats.c:2
witness_assert
void witness_assert(const struct lock_object *lock, int flags, const char *file, int line)
Definition: subr_witness.c:2426